Force Feedback Model of Electro-hydraulic Servo Tele-Operation Robot Based on Velocity Control

A tele-operation robotic system using bilateral control is useful for performing restoration in damaged areas, and also in extreme environments such as space, the seabed and deep underground. The system consists of an excavator as the construction robot, and two joysticks for operating the robot from a safe place. Operator needs to feel a realistic sense of task force brought about from a feedback force of the fork glove. A new force feedback model is proposed between fork glove and environments based on velocity control of cylinder to determine environment force acting on fork glove. Namely, the reaction force is formed by the error of displacement of joystick with velocity and driving force of piston, and the gain is calculated by the driving force and threshold driving force. Moreover, the variable gain is developed for grasping soft object. Experimental results are given to demonstrate the proposed algorithm has good stability and transparency for grasping soft object.